The present invention relates to a process for reusing plastic articles with coatings, and more particularly to an improvement in a process for reusing plastic articles from which coatings are peeled apart by using a high pressure water jet stream. For reusing the plastics, the plastic articles are to be pulverized.
Conventionally, plastic articles with coatings have been pulverized by a pulverizing machine without peeling off the their coatings, and the pulverized plastics are molded by injection molding machines or press molding machines for reuse articles.
It has been proposed to reuse the plastic articles after coatings are removed therefrom. Recently, some methods for peeling the coatings with organic solvent have been proposed. For instance, the plastic articles with coating layers are pulverized; the pulverized articles are dipped into a solvent tank filled with organic salts or the like; only the plastic components are removed by a separator; and further after washing and drying, the articles are pelletized by an extruder for reuse.
However, the convention reuse methods suffer from the following disadvantages:
(1) In the former conventional case, since the coating material and the plastics are mixed with each other, the coating material would affect adversely the reuse articles to degrade the quality of the articles. The coating pieces contained in the reused articles will reside therein as inpurities, resulting in degradation of the material strength. Also, the coating pieces are irregularly dispersed on the surface of the articles, which degrade the aesthetic appearance thereof. The use thereof is largely limited to, for instance, benches in a public park, fences or blocks for pavements, or the like. It would be impossible to use the reuse article without limitation. PA1 (2) In the latter conventional case, since organic salts or the like are used, if the used solvent would be disposed without any treatment, a problem of public pollution would be raised. It is therefore necessary to make it innoxious. However, this causes an unduly high cost. Also, water to be used for washing must be kept harmless, which needs a large-scale system for such an innocuous property. PA1 (3) The coating material is readily separated from the plastic pieces in the solvent. It is however very difficult to accurately remove the plastic pieces from the solvent. It is inevitable for the final articles to contain the coating material, which would lead to the degradation in quality of the reuse articles.
As mentioned above, the reuse plastics may be used only for articles which might be classified in a low level in quality.